Dissertations / Theses on the topic 'Missile Antennas'

ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, Nevada
Multiple discrete antennas distributed around the circumference of a large missile and driven by one transmitter are sometimes used to radiate telemetry omnidirectionally. But driving discrete antennas separated by several wavelengths around the missile body with a single transmitter can result in an antenna pattern with deep nulls in the roll plane. Varying the relative signal phase or amplitude among the signals driving the antennas as well as the polarization of the antennas can be used to change the nulls in an attempt to decrease the null depth. In this paper the effects of phase, amplitude, and polarization on the roll-plane pattern are examined and measurement data presented.

Thesis (M.S. in Physics)--Naval Postgraduate School, June 2003.
Thesis advisor(s): Michael Melich, David Jenn, Rodney Johnson. Includes bibliographical references (p. 113-115). Also available online.

Optimal missile guidance and flight performance require accurate and continuously updated in-flight coordinate data. The Global Positioning System (GPS) is used for this positional awareness. However, due to missile rotation and orientation variations during flight, GPS signal reception using traditional antennas may be intermittent. To remain cost competitive, Stellar Exploration Inc. is developing a low-cost omnidirectional GPS antenna for guided missile prototypes. In this thesis, existing products and design techniques are examined, design constraints for supersonic missile applications are investigated, and corresponding performance goals are established. A conformal microstrip patch antenna is developed and simulated in Agilent’s Advanced Design System (ADS). The resulting antenna is constructed and characterized. Prototype testing verifies that the antenna maintains GPS signal lock regardless of orientation. The final cost is significantly lower than existing conformal products. A second revision investigates enhanced modeling, dimensional reductions (via increased dielectric constant), and radome construction. Performance is compared to first revision antenna results and differences are examined. Suggestions for further revisions are discussed.

This thesis work describes a brand new concept of how to, from a mechanical perspective, stabilize/mount a radar antenna. The antenna must be able to rotate ±60 degrees around pitch and yaw without disturbing the radar characteristics. At the same time the antenna diameter must be as large as possible to enhance radar quality. Axiomatic Design was applied as the work method which helped developing a brand new concept of how to mount the antenna. This concept study was made for Saab Bofors Dynamics at Massachusetts Institute of Technology in the lab ”Park Centre for Complex Systems” under supervision of Prof. Nam P. Suh (MIT) and Jan-Gunnar Persson (KTH). The invention process using Axiomatic Design resulted in a brand new concept. A fixed sphere, in which the antenna can slide, eliminates the translational degrees of freedom. Two linkages actuate the antenna by means of linear motors. A careful selection of joints eliminates the last unwanted degree of freedom. Left are two rotational DOF, one around pitch and one around yaw. Only the thickness of the sphere and the missile inner diameter limit the size of the antenna diameter. The radar disturbance is remaining low, since the additional disturbance is very low and the same in every angle in the ±60 degree of freedom that the antenna has. That is achieved by letting the antenna slide inside a sphere where the walls are equally thick all around the required work space. The material of the sphere could preferably be the same as in the radome. Oversteering is minimized since direct drive is possible. No transmission is needed. The antenna has physical restrictions at 90 degrees. Since that is outside the work space it does not affect the rotation mechanism.
Denna rapport beskriver en konseptstudie på hur man på olika sätt kan rotera en två frihetsgraders radarantenn. Antennen har rörelsekrav på ±60 grader kring tilt samt elevation. Den ska placeras inuti en missil, vilket ger den utrymmesrestriktioner. För att optimera antennens kvalitet får antennens microvågor störas minimalt samtidigt som antennens diameter måste vara så stor som möjligt. Axiomatic Design har tillämpats som utvecklingsmetod för att komma fram till ett konstuktionskoncept. Denna konseptstudie har utförts för Saab Bofors Dynamics vid Massachusetts Institute of Technology, MIT under ledning av Håkan Skytt (Saab Bofors Dynamics) och Nam P. Suh (MIT) och Jan-Gunnar Persson (KTH). Efter att ha värderat olika lösningsförslag med hjälp av Axiomatic Design valdes ett koncept refererat som Fixed Sphere. Antennen slider m h a lågfriktionsytor inuti en sfär. Två länkar med linjära motorer i respektive länk vrider antennen. Noggrant utvalda leder begränsar antalet frihetsgrader hos antennen till de önskade frihetsgraderna. Sfären maximerar storleken hos antennen. Bara sfärens väggtjocklek, samt missilens yttervägg begränsar antennens diameter. Mikrovågorna, vars kvalitet är av yttersta vikt, försämras marginellt då samma typ av material väljs som används till radomen på missilen. Sfärens geometri gör att den tillkomna störningen är konstant, oavsett hur antennen vrider sig inom arbetsområdet ±60 grader. Detta är åstadkommet genom att väggtjockleken är konstant genom hela arbetsområdet. Det gör att mängden material m a o väggtjockleken som radarn ser igenom är konstant oavsett vinkel. Överstyrdheten hos radarn antas elimineras då motorerna kan direktköras. Det finns inga kugghjul som kan skapa och sprida glapp. Rörlighetsförmågan hos antennen har restriktioner kring ±90 grader, men då detta ligger utanför arbetsområdet kan det bortses ifrån.

Ce memoire presente une etude theorique d'un systeme actif de reduction de la surface equivalente radar (s. E. R. ) monostatique de missiles, supposes parfaitement conducteurs, dans leur zone de resonance. L'analyse du comportement electromagnetique d'un mobile face a une onde radar incidente est tout d'abord effectuee. La methode de resolution d'un tel probleme est basee sur l'etude de la diffraction d'ondes electromagnetiques par des structures conductrices en regime transitoire. Le champ electromagnetique diffracte par une cible est calcule en zone proche par une methode aux differences finies, l'application du principe d'huygens permet ensuite de determiner le champ a grande distance, et d'en deduire la s. E. R. . L'outil numerique a ete valide en confrontant les resultats a des resultats experimentaux ou theoriques utilisant des methodes differentes. Le principe de reduction de la s. E. R. Propose repose sur le pilotage de quatre antennes plaquees reparties sur le missile. L'application en temps reel de puissances et phases adequates a chacune de ces antennes permet de generer dans la direction du radar un champ electromagnetique en opposition de phase avec celui diffracte par le missile dans la meme direction. La modelisation numerique du mobile muni de ses antennes a permis de calculer les caracteristiques des alimentations permettant une annulation de la surface equivalente radar monastatique de la structure sans demander aux generateurs des puissances disponibles prohibitives. L'etude de la sensibilite des resultats a diverses sources sources d'erreurs a montre l'attention qui devra etre apportee aux mesures et calculs des differents parametres du systeme de compensation de la s. E. R.

ITC/USA 2011 Conference Proceedings / The Forty-Seventh Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2011 / Bally's Las Vegas, Las Vegas, Nevada
This paper will present the preliminary design of a C-Band telemetry antenna mounted conformal to a small diameter missile. Various design studies and options will be explored leading to a preliminary design that best meets system requirements. Simulation results are presented for various options and the rationale for down selection to final configuration is discussed.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada
Telemetry support has been a component of the instrumentation test support structure at Kwajalein Missile Range (KMR) for nearly 40 years. From a limited initial suite of manually pointed telemetry antennas, the Range has grown to include nine tracking antennas and four fixed receiving antennas. This paper describes the current modernization program at KMR that will include nine new telemetry trackers and five fixed antennas that will be networked and controlled via fiber optic links from a newly established telemetry control center on the island of Kwajalein. These upgrades will reduce operational cost and institute efficiencies, while continuing to meet Range Users’ growing requirements.

Thesis (M.S. in Combat Systems Technology)--Naval Postgraduate School, December 2005.
Thesis Advisor(s): David C. Jenn, Donald L. Walters. Includes bibliographical references (p.83-85). Also available online.

International Telemetering Conference Proceedings / October 22-25, 2001 / Riviera Hotel and Convention Center, Las Vegas, Nevada
During these times of acquisition reform in the federal government, various missile systems are being forced into using Commercial-off-the-Shelf (COTS) products in the design of their subsystems. However one problem that this presents is the lack of configuration management. There is a concern that the manufacturer will modify the product without informing the end user. This may have a severe effect on the performance of an already flight qualified subsystem. An example of how one program is dealing with this issue will be discussed.

ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California
Development is currently underway to produce a dual redundant Flight Termination System (FTS) capable Missile Telemetry Section. This FTS will mainly consist of a conformal wraparound antenna, two flight termination safe & arm (FTS&A) devices, two flight termination receivers (FTR), two explosive foil initiators (EFI) and destruct charge. This paper will discuss the current status of the development of these FTS components along with the process of obtaining the Flight Certification from Range and System Safety to fly this newly outfitted missile on a governmental test range.

Thesis (M.S. in Aeronautical Engineering (Avionics)) Naval Postgraduate School, September 1996.
Thesis advisor(s): David C. Jenn, Robert E. Ball. "September 1996." Includes bibliographical references (p. 69). Also available online.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada
This paper describes the design, configuration, testing, and performance of a Fiber Optic Link used to transmit the signals from a remotely located S-band telemetry system to the main facility at the Kwajalein Missile Range (KMR). This fiber optic system demonstrates for the first time the feasibility of linking RF data from multiple antennas via a single fiber and over a nearly 100-km distance. Measured data of key link parameters such as gain, bit-error-rate, crosstalk, phase and gain stability, dynamic range, and noise figure are presented.

ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV
Functionally testing missiles in the All Up Round (AUR), a configuration that consists of a complete system packaged in its flight worthy state, requires the use of test sets along with constituent conformal equipment for interfacing. During developmental testing, telemetry (TM) sections are integrated within an AUR missile. These test sets monitor TM unit performance while maintaining form, fit, and function; therefore, resulting in complete data confidence. Initiating TM functional tests permit a capability in verifying that TM sections have been integrated properly. Safety being a priority, in order to attenuate RF radiation leakage while providing repeatable test capabilities in the near-field, antenna couplers are fabricated as a shielding interface between the user and radiating source and a coupling interface between an AUR missile and the test set. Generally, antenna couplers are composed of metallic bodies which require machine shop fabrication. The process of getting machined parts can take up to several months which can delay delivery schedules. With the availability of 3D printing capabilities and methods in metalizing various materials, a novel approach to fabricating antenna couplers has been explored. The use of modeling Software Packages (Computer Aided Design and Electromagnetic Solvers) and additive printing play key roles in reducing the development cycle time while saving costs, decreasing weight, and sustaining performance. This paper will detail the efforts using 3D printing capabilities in the development and fabrication of an antenna coupler with several examples cited herein.

Cette étude est réalisée dans le cadre de la mission spatiale EXOMARS, en collaboration avec LATMOS (Laboratoire Atmosphères, milieux, observations, spatiales). Les objectifs sont explorer la planète Mars pour la recherche de signes de vie passée ou présente, l’étude de la distribution de l’eau dans le sous sol martien et l’étude de la géologie de Mars. Cette mission consiste à envoyer sur la surface de Mars un véhicule automatisé équipé d’instruments de mesures scientifiques destinés à la recherche de traces de vie. Notre activité de recherche s'est focalisée sur l’instrument WISDOM (Water Ice Subsurface Deposits Observation On Mars) qui est un GPR (Ground Penetrating Radar) dont les principaux objectifs scientifiques sont de sonder le sous-sol de Mars jusqu’à quelques mètres de profondeur pour étudier les structures géologiques. Notre travail s'est déroulé en trois phases. La première a consisté à trouver un modèle de rayonnement large bande permettant de modéliser le rayonnement des antennes du GPR. La deuxième a permis de développer des outils permettant de simuler des scènes de différentes compositions en optimisant le temps de calcul. La troisième phase de cette thèse a permis de développer deux techniques permettant de caractériser une surface rugueuse. Ainsi cette approche sera exploitée pour ensuite développer deux méthodes de calcul de la permittivité du sol en temporel et en fréquentiel
This study is a part of the ExoMars space mission, in collaboration with LATMOS (Laboratoire Atmosphères, milieux, observations, spatiales). The objectives are to explore the signs of life on Mars planet in the past or in the present time, as well as the study of the distribution of subsurface water and the study of the geology of Mars. This aim of this mission is to send on the Mars surface an automatic vehicle equipped with scientific measuring instruments intended for the search of life traces. Our research activity is focused on the WISDOM instrument (Water Ice Subsurface Deposits Observation On Mars) which is a GPR (Ground Penetrating Radar) where the main scientific objectives are to probe the subsurface of Mars up to several meters in order to study the geological structures. Our work have been proceeded in three phases. The first was to find a broadband radiating model of modelling the radiation pattern for the GPR antennas. The second was to develop tools for simulation scenes of different compositions by optimizing the computing time. The third phase of this thesis permits to develop two techniques for rough surfaces characterization. Thus this approach will be exploited for the development of two methods for the determination of the permittivity of the ground in time and frequency domain

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering In the Faculty of Engineering at the Cape Peninsula University of Technology, 2013
The French South African Institute of Technology (F’SATI) at the Cape Peninsula University of Technology (CPUT) began a program in Satellite Systems Engineering in 2009 and is developing its first satellites. The satellites are based on the CubeSat standard, which defines one unit (1U) as a cube with a maximum weight of 1 kg and volume of 1dm3, and can be scaled up to three units (3U) for increased functionality. ZACUBE-1, a 1U CubeSat that is being developed, will be launched into a sun synchronous orbit in 2013. The main payload of the 1U CubeSat under development is a space weather experiment (beacon transmitter). The beacon transmitter is a scientific payload, which is being developed in collaboration with SANSA Space Science (SANSA SS) in Hermanus, South Africa. The beacon signal will be used to characterise the space weather radar antenna array at the South African National Antarctic Expedition (SANAE IV) base in Antarctica. The SANAE IV radar forms part of the SuperDARN (Dual Auroral Radar Network) project. This phased array antenna network comprises 16 radiating elements, with a 3o beam width that can be steered in 16 different directions to span the azimuth sector. These antennas are spread over both the northern and southern hemispheres. They operate in the HF band between 8 to 20 MHz and are used to primarily monitor the convection of the Earth’s magnetic field by monitoring coherent scatter from it. Orbital analyses were conducted to determine how the choice of the orbit affects the coverage of the array’s field-of-view. Propagation analyses were conducted to investigate how space weather variations affect HF signal propagation. The beacon signal will be used as an active target source and will enable the determination of the phase response of the array, thereby determining the direction-of-arrival of the signal. This will allow the experimental verification of the antenna’s beam pattern. The beacon signal prototype board was developed by using an RFID transceiver that operates in the HF band, capable of delivering up to 200 mW. Position determination of the satellite will be done by using two line elements (TLE) data. Experimental data will be available once ZACUBE-1 is in orbit; therefore, the work presented here documents a feasibility study and design of the experiment that will be conducted once the satellite is in orbit.

La mutation contemporaine des milieux protestants engagés de Norvège et de Suède, secteur encore largement méconnu de la recherche française, se traduit par l’adaptation structurelle et idéologique des organisations missionnaires Normisjon, Norsk Luthersk Misjonssamband, Norsk Misjonsselskap, Indremisjonsforbundet et Norme, et des deux antennes de jeunesse equmenia et Acta à la remise en question de leur statut culturel dominant. Elles sont amenées à adopter des comportements proches d’une communauté religieuse, à se restructurer, à mettre en évidence des réseaux transconfessionnels nouveaux et à orienter leurs objectifs autour de leur projet militant. Retraçant l’évolution des mouvements populaires, sous la forme des réveils et sous leur recomposition actuelle, il s’agit de comprendre les problématiques sous-jacentes réactualisées par une telle mutation. Que ce soit sous les formes de l’œcuménisme moderne, la globalisation des enjeux missionnaires, le défi de la transmission intergénérationnelle ou le souci d’une rationalisation économique et matérielle, ces raisons ont souvent en commun d’appréhender le phénomène à la lumière des enjeux rencontrés sur le plan interne. Pourtant, les mutations observées (statut, structure, objectifs) doivent être lues comme des problématiques transversales qui montrent les limites d’une approche ciblée et exigent une analyse de ce secteur dans une perspective de recherche distincte dans l’histoire contemporaine et la sociologie des religions en Scandinavie
The contemporary mutation of Norwegian and Swedish Protestant circles, a sector largely unknown to French research, may be analyzed through the recent structural and ideological adaptation of the following missionary organizations Normisjon, Norsk Luthersk Misjonssamband, Norsk Misjonsselskap, Indremisjonsforbundet and Norme, as well as of two youth antennae equmenia and Acta. They are led to espouse behavioral patterns bearing resemblance with the ones of a religious community: they restructure, highlight trans-confessional networks and reframe and recast their objectives in the light of their militancy and militant objectives. Retracing the trajectory of popular movements through the “awakenings” and present-day metamorphoses, the aim is here to analyze the underlying re-actualizations at stake in this contemporary transformation. Be it in the form of modern ecumenism, the globalization of missionary issues, the challenge of trans-generational transmission or the imperative of economic and material rationalization, these reasons often have in common to highlight the phenomenon from the point of view of its internal factors and impetuses. However, the socio-historical conditions and the transformations (status, structure, objectives) that we highlight have simultaneously to be understood in the context of broader transversal dynamics, thus highlighting the limits of a “targeted” approach and calling for an analysis of the aforementioned sector as a distinct field of research within the sociology of religions in Scandinavia

Thesis (M.S. in Systems Technology (Command, Control, and Communications (C3)))--Naval Postgraduate School, September 2007.
Thesis Advisor(s): Ehlert, James. "September 2007." Description based on title screen as viewed on Oct. 23, 2007. Includes bibliographical references (p. 85-86). Also available in print.

La sonde Cassini, lancée en 1997 et arrivée dans le système de Saturne début Juillet 2004, acquiert des images de la surface de Titan dans le proche-infrarouge, l'infrarouge moyen et le domaine des ondes radio (radar). Jusqu’à cette date, la surface de Titan, recouverte d’une atmosphère épaisse, riche en méthane et opaque en lumière visible, était restée inconnue. Le travail principal de cette thèse consiste à analyser les données acquises par VIMS (Visual and Infrared Mapping Spectrometer), afin de cartographier la surface de Titan. Pour chaque pixel d'une image, VIMS permet d'enregistrer un spectre complet entre 0. 35 et 5. 11 μm. Les spectres présentent différentes fenêtres atmosphériques à travers lesquelles la surface est visible. Grâce à la création de mosaïques d'images à l'échelle globale, différents types de terrains ont pu être identifiés. Les données VIMS et les images radar en mode SAR sont combinées dans un système d'information géographique pour étudier les structures géologiques : cryovolcans, champs de dunes, lacs, chenaux et cratères d’impact. Ces structures ont une bonne corrélation entre les morphologies observées en radar et en infrarouge. L'étude d'une coulée cryovolcanique en particulier montre que sa composition est compatible avec un mélange de glace de CH4, H2O, CO2. La cartographie globale du satellite permet d'étudier la distribution des structures géologiques, des différentes unités et la corrélation radar/infrarouge afin de comprendre la nature de ces terrains et les processus d'érosion existants à la surface de Titan. L'âge de la surface de Titan est estimée entre 200 Ma et 2 Ga à partir des cratères recensés sur les images radar
Cassini spacecraft, launched in 1997 and arrived in July 2004 at Saturn, provides images of Titan's surface in the near-infrared, medium infrared ranges and in the radio wavelengths range corresponding to the Cassini radar instrument. Previously, Titan’s surface, hidden by a thick methane-rich atmosphere opaque for the visible light, was unknown. The main work in this thesis is to analyze the dataset acquired by VIMS (Visual and Infrared Mapping Spectrometer), in order to map Titan's surface. For each pixel of an given image, VIMS observes a spectrum between 0. 35 and 5. 11 μm. Atmospheric windows of methane allow to see the surface through the haze of aerosols and gases. By creating global mosaics of infrared images, we can infer different types of terrains. Geological features, such as cryovolcanoes, dune fields, lakes, fluvial channels, and impact craters, are studied thanks to the combination of VIMS et radar images in SAR mode in a geographic information system. They show a good correlation in morphology between radar and infrared datasets. The study of a particular cryovolcanic flow demonstrates that the composition can match spectra of mixtures of ices containing CH4, H2O, and CO2. Global mapping is useful to study the spatial distribution of geological units, features and correlation between datasets aiming to understand the nature and erosion processes prevailing on Titan's surface. A global crater count using the available radar swaths permits to estimate the surface age between 200 Myr and 2 Gyr

La thèse s'inscrit dans le cadre des travaux préparatoires à la mission spatiale BIOMASS du programme Earth Explorer de l'ESA (Agence Spatiale Européenne), qui prévoit d'exploiter pour la première fois depuis l'espace un SAR en bande P (435 MHz), dans le but de cartographier la biomasse et la hauteur des forêts à l'échelle globale pour la période 2023-2028. L'utilisation de la bande P permet d'obtenir une sensibilité du signal inédite avec la biomasse, en lien avec ses capacités de pénétration même à travers des forêts tropicales denses. La mission BIOMASS se base sur l'utilisation conjointe de trois méthodes d'imagerie qui sont la Polarimétrie (PolSAR), l'Interférométrie (PolInSAR) et la Tomographie (TomoSAR). Ses objectifs sont de produire tous les 7 mois des cartes de biomasse et hauteur des forêts à la résolution de 4 ha, ainsi que des cartes des perturbations sévères à 0.5 ha. La thèse s'est organisée autour du développement d'une chaîne de calcul articulée en plusieurs modules permettant d'extraire des valeurs de biomasse à partir de données PolSAR en bande P dans la perspective de cartographier la biomasse forestière de manière robuste et automatique. Les deux modules principaux consistent à estimer un indicateur polarimétrique lié à la biomasse forestière puis à l'inverser en biomasse en appliquant une méthode bayésienne construite sur des grandeurs a priori issues d'un modèle électromagnétique prédictif (MIPERS-4D). Une étude a été consacrée à la comparaison de différents indicateurs PolSAR permettant l'inversion de la biomasse forestière sur les différents sites expérimentaux étudiés. Cette thèse aborde la possibilité de minimiser les effets de la topographie avec une utilisation conjointe des modèles numériques d'élévation (DEM) qui donnent une approximation des pentes sous forêts et des données PolSAR à partir desquelles il est possible d'extraire des informations sur les coefficients des matrices de covariances et sur les pentes azimutales sous forêt. Dans l'objectif d'améliorer les relations entre les coefficients de rétrodiffusion et la biomasse, la minimisation des effets de speckle a également été étudiée dans le cadre des scénarios d'acquisitions BIOMASS, supposant des adaptations des techniques de filtrage existantes pour des séries temporelles de données SLC polarimétriques. Ces travaux sur le développement d'un filtre multi-temporel et multi-canal adapté aux séries temporelles PolSAR ont été valorisés dans l'article "Multi-temporal speckle filtering of polarimetric P-band SAR data over dense tropical forests in French Guiana : application to the BIOMASS mission" (publié dans la revue Remote Sensing), dans lequel un nouvel indicateur permettant de quantifier les performances du filtrage a également été proposé, en lien avec la capacité inédite de ces données pour caractériser les pentes azimutales du terrain. Ces différents travaux ont permis de mettre au point une méthode d'inversion adaptable aux contraintes de généralisation spatiale et temporelle pour les futures acquisitions BIOMASS à l'échelle globale. La méthode développée repose sur la combinaison d'un indicateur issu des données PolSAR qui optimise la relation à la biomasse ainsi que d'une méthode bayésienne minimisant les effets de dispersion à partir de fonctions de vraisemblance issues du modèle MIPERS-4D. Les conditions d'observations peuvent ainsi être prises en compte au travers de la paramétrisation du modèle, et l'application de cette méthode aux données des campagnes aéroportées étudiées dans cette thèse a montré son intérêt pour éviter la propagation directe des effets temporels ou de structure en biomasse. La combinaison de ces différentes études a permis d'améliorer la méthode d'inversion tout au long de la thèse, en ouvrant également des perspectives de développement pour la consolider avec en particulier la généralisation aux indicateurs PolInSAR et TomoSAR, en vue d'une exploitation la plus complète des futures données BIOMASS
This thesis took place during the preparation phase of the BIOMASS ESA (European Space Agency) mission, which plans to exploit for the first time ever a P-band (435 MHz) spaceborne SAR, with the aim at mapping forest biomass and height worldwide for the period 2023-2028. The use of the P-band comes from its unique sensitivity to forest biomass, in relation to its ability to penetrate through dense media like tropical forests. The BIOMASS mission is based on the use of three imaging modes: Polarimetry (PolSAR), Interferometry (PolInSAR) and Tomography (TomoSAR), and aims at delivering forest biomass and height maps every 7 months at a resolution of 4 ha, as well as maps of severe disturbances at 0.5 ha. The thesis has been organised around the development of a processing chain made of several modules in order to map forest biomass from P-band PolSAR images, and for a wide range of forest types and observation conditions. The two main modules consist in the development of a PolSAR indicator related to forest biomass and in a Bayesian method built on likelihood functions derived from a predictive electromagnetic model (MIPERS-4D). A first study focused on the comparison between various PolSAR based indicators adapted to forest biomass estimation on several test sites. In particular, this thesis emphasises the possibility of minimising the effects of topography with the joint use of digital elevation models (DEM) which give an approximation of terrain slopes and with the fully polarimetric covariance matrix from which it is also possible to extract topographic information like the azimuthal component of terrain slopes. In order to improve the link between backscatter coefficients and biomass, the minimisation of speckle effects has also been studied in the specific framework of BIOMASS acquisitions plan, meaning the adaptation of state-of-the-art filtering techniques for polarimetric SLC time series data. This work results in the development of a multi-channel filter adapted to PolSAR time series, which has been demonstrated on the TropiSAR data acquired at the Paracou test site, and described in the paper "Multi-temporal speckle filtering of polarimetric P-band SAR data over dense tropical forests in French Guiana: application to the BIOMASS mission", published in the journal Remote Sensing, in which a new indicator to quantify filtering performances has been also highlighted, in connection with the capacity of P-band PolSAR data to characterise the azimuthal slopes. These works contribute to develop an inversion method accounting for the challenging constraints of spatial and temporal generalisations for the future BIOMASS acquisitions at global scale. The developed method proposes the combination of the so-called t0 indicator derived from PolSAR data in order to optimise the relationship with forest biomass, with a Bayesian method minimising the dispersion effects thanks to likelihood functions derived from the MIPERS-4D model. The observation conditions related to the temporal or spatial variability can be thereby accounted for, and application of the method to the P-band airborne SAR data acquired during the BIOMASS mission preparation phases shows its great interest to avoid the direct propagation of dispersive factors into biomass. These contributions enabled to adapt and improve the processing chain, and paved to way to further prospects of new insights such as the method generalisation with PolInSAR and TomoSAR indicators, in order to achieve a more thorough exploitation of the upcoming BIOMASS data

En lien avec les activités humaines et l’élévation du niveau de la mer dans le cadre du changement climatique, les zones intertidales sont soumises à de fortes pressions. La topographie de ces environnements est ainsi en évolution permanente. Le suivi de la topographie est fondamental pour la modélisation hydrodynamique et morphodynamique des systèmes côtiers. Ce suivi fait face à des importantes difficultés, surtout sur le plan logistique, vu la localisation des zones intertidales entre les limites des plus hautes et des plus basses marées. La télédétection spatiale est une des meilleures approches pour assurer des mesures topographiques intertidales à jour dans l’espace et dans le temps. Cette thèse porte ainsi sur l’utilisation de la télédétection spatiale pour le suivi de la topographie des zones intertidales par des capteurs radar (altimétrie et Radar àSynthèse d’Ouverture (RSO)) et multispectrales. L’objectif principal est d’explorer, de développer ou d’améliorer des méthodes dédiées à la cartographie de la topographie intertidale, et d’étudier également la capacité de la future mission SWOT (Surface Water and Ocean Topography; première mission altimétrique à fournir des élévations au sein d’une fauchée au moyen de la technique d’interférométrie SAR (RSO)) à cartographier la topographie de ces zones. Les méthodologies développées et utilisées dans cette thèse ont été appliquées à deux baies intertidales situées sur la façade Atlantique de la côte française : Le Bassin d’Arcachon et la Baie des Veys. Nous avons d’abord montré que les améliorations techniques des nouvelles missionssatellitaires permettaient, pour la première fois, à l’altimétrie satellitaire de fournir des profils topographiques intertidaux le long des traces des altimètres. Deuxièmement, nous avons introduit une approche améliorée de la méthode de la ligne d’eau (méthode la plus courante pour la cartographie de la topographie intertidale) qui sert à générer des Modèles Numériques d’Élévation (MNEs) intertidaux à l’aide des images satellitaires (RSO et multispectrales). Grâce à cette nouvelle approche, la détection des lignes d’eau et leurs post-traitements sont maintenant plus rapides, plus efficaces et quasi-automatiques. Nous avons également mis en évidence la capacité de SWOT à générer des MNEs intertidaux précis en utilisant la méthode de la ligne d’eau. Les méthodologies développées et utilisées au cours de cette thèse sont capables de mesurer régulièrement latopographie dans les zones intertidales et permettre la détection des changements topographiques dans ces environnements et proposer des bilans morpho-sédimentaires. Ainsi, les deux zones intertidales étudiées sont en érosion sur la période de 2016 à 2018 avec des pertes en volume de 1,12 × 106 m3 et 0,70 × 106 m3 pour le bassin d’Arcachon et la baie des Veys respectivement. Ces informations sont utiles et nécessaires pour plusieurs applications scientifiques (par exemple, le bilan sédimentaire, la modélisation hydrodynamique), mais aussi pour les autorités et les acteurs du littoral dans le but de la mise en oeuvre des politiques d’utilisation et de protection de ces environnements
Intertidal flats provide essential services including protection against storm surges and coastal flooding.These environments are characterized by a continuous redistribution of sediments and topographic changes.They are under increasing pressure due to anthropogenic activities and sea level rise. The continuous monitoring of their topography is fundamental for hydrodynamic and morphodynamic modeling of coastal systems. Intertidal flats are among the most logistically challenging coastal landforms for ground-based and airborne-based topography monitoring. Spaceborne-based monitoring is the only viable and the mostcost-effective approach capable of providing regularly intertidal topography maps. Recent developments in radar (altimetry and Synthetic Aperture Radar (SAR)) and optical technologies, bring new types of data and enhanced capacities for monitoring intertidal environments. This PhD dissertation investigates the use of spaceborne-based methods for monitoring the topography in intertidal areas using radar altimetry, SAR, and multispectral satellite observations. The main objective is to explore, develop, or enhance methods dedicated for intertidal topography mapping. Being a part of the preparation phase of the future SWOT (Surface Water and Ocean Topography) radar altimetry mission, first mission to operate in wide-swath SAR interferometrymode, this PhD dissertation also investigates the capability of SWOT to map intertidal topography. Methodologies developed or/and used in this thesis were applied to two intertidal environments located on the French Coast: The Arcachon Bay and the Bay of Veys. We showed, for the first time, that recent advancements in technologies enabled satellite radar altimetry to extract intertidal topography profiles along the altimeters ground tracks. Second, we introduced an improved and quasi-automatic approach for the use of the waterline method (most common method for intertidal topography mapping) to derive intertidalDigital Elevation Models (DEMs). The changes include faster, more efficient and quasi-automatic detection and post-processing of waterlines. We also brought to light the ability of SWOT to generate highly accurate intertidal DEMs using the waterline method. The methodologies used here allow the generation of intertidal topography measurements regularly, that with careful usage, can be used for detecting topographic changes in intertidal environments. We showed that the two study areas eroded during 2016-2018, losing 1,12 × 106 m3 and 0,70 × 106 m3 for the Arcachon Bay and the Bay of Veys respectively. Updated DEMs provide useful and needed information for several scientific applications (e.g., sediment balance, hydrodynamic modelling), but also for authorities and stakeholders for coastal management and implementation of ecosystem protectionpolicies